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perf_counter: Sanitize context locking

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Ensure we're consistent with the context locks.

 context->mutex
   context->lock
     list_{add,del}_counter();

so that either lock is sufficient to stabilize the context.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <20090523163012.618790733@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2009-05-23 18:28:57 +02:00 committed by Ingo Molnar
parent fccc714b31
commit 682076ae1d
1 changed files with 7 additions and 2 deletions
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9
kernel/perf_counter.c
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@ -597,6 +597,8 @@ static void add_counter_to_ctx(struct perf_counter *counter,
/*
* Cross CPU call to install and enable a performance counter
*
* Must be called with ctx->mutex held
*/
static void __perf_install_in_context(void *info)
{
@ -1496,13 +1498,13 @@ static void perf_counter_for_each_sibling(struct perf_counter *counter,
struct perf_counter_context *ctx = counter->ctx;
struct perf_counter *sibling;
spin_lock_irq(&ctx->lock);
mutex_lock(&ctx->mutex);
counter = counter->group_leader;
func(counter);
list_for_each_entry(sibling, &counter->sibling_list, list_entry)
func(sibling);
spin_unlock_irq(&ctx->lock);
mutex_unlock(&ctx->mutex);
}
static void perf_counter_for_each_child(struct perf_counter *counter,
@ -3414,7 +3416,10 @@ __perf_counter_exit_task(struct task_struct *child,
struct perf_counter *parent_counter;
update_counter_times(child_counter);
spin_lock_irq(&child_ctx->lock);
list_del_counter(child_counter, child_ctx);
spin_unlock_irq(&child_ctx->lock);
parent_counter = child_counter->parent;
/*